JP2003285210A - Drill and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drill and its manufacturing method free from any breakage due to chip clogging even if it has a longer cutting blade. <P>SOLUTION: The drill body 11 rotating around an axis line O is provided with a chip disposal channel 15 along its top end periphery, and a cutting blade 18 is formed on a crossed edge line area between a rake face 17 formed on the end side of an inner circumference 16 of this chip disposal channel 15 and a tip flank 14 of the drill body 11. The channel bottom 24 of the chip disposal channel 15 is formed so that the cutting of it begins from the rear end 20 of this chip disposal channel 15 towards the end side of the axis line O within the range of L/2 of the chip disposal channel 15 length L, allowing the curvature radius R shaped as a concave curve of 10×D or more or a straight line to reach the rear end 20 on a cross section along the direction of the chip disposal channel 15 extending. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly includes a chip discharge groove formed on the outer periphery of the tip of a drill body, and a cutting blade provided on the tip of the inner peripheral surface of the chip discharge groove facing the direction of rotation of the drill. The present invention relates to a drill used for drilling a workpiece made of a metal material.

[0002]

2. Description of the Related Art As such a drill, for example, FIG.
The rear end side of the substantially cylindrical drill body 1 rotated in the drill rotation direction around the axis O as shown in Fig. 2 is the shank portion 2 gripped by the spindle of the machine tool, and the tip side is The cutting edge portion 3 is provided with a pair of chip discharge grooves 4 and 4 on the outer periphery of the cutting edge portion 3 so that the cutting edge portion 3 is symmetrical with respect to the axis O, that is, the tip of the drill body 1. Axis O as it goes from the flank 5 to the rear end side
A ridge line intersecting with the tip flank 5 on the tip side of the inner peripheral surface of the chip discharge grooves 4, 4 which is twisted rearward in the drill rotation direction and faces the drill rotation direction. There is known a so-called two-flute solid drill having a cutting edge 6 formed on its part. Therefore, in such a solid drill, the tip side of the inner peripheral surface of the chip discharge groove 4 facing the drill rotation direction becomes the rake face 7 of the cutting blade 6,
The chips generated by the cutting blade 6 are sent to the rear end side by the twist of the chip discharge groove 4 while being in sliding contact with the inner peripheral surface of the chip discharge groove 4 from the rake face 7 and discharged.

Here, the groove bottom 8 at the rear end portion of the chip discharge groove 4 in such a drill is the chip discharge groove 4
Along the extending direction of the chip, that is, the chip discharge groove 4
4 is twisted as described above, in the cross section along the twist, as shown in FIG. 4, the cutting edge portion 3 is cut up toward the outer peripheral side of the rear end so as to form a concave curve with a relatively small radius of curvature. Is formed so as to reach the outer peripheral surface of the chip, and the position where the groove bottom 8 is cut up and reaches the outer peripheral surface of the cutting blade portion 3 is the rear end of the chip discharge groove 4. This is because the groove bottom 8 of the chip discharge groove 4 rotates the disk-shaped grinding wheel G around its central axis X as shown in FIG. The grinding wheel G and the drill body 1 while sliding on the surface.
And relative movement in the direction of the axis O (normally, the drill body 1 is moved while the grinding wheel G is fixed, and the grinding wheel G escapes as shown by the arrow A in FIG. Formed by moving the surface 5 toward the rear end side relative to each other. At the rear end of the chip discharge groove 4, the rotation of the grinding wheel G is stopped when the chip discharge groove 4 is formed to a predetermined position. This is because the groove is taken out from the discharge groove 4, and therefore the radius of curvature of the concave curve formed by the above-mentioned cross section of the groove bottom 8 at this rear end is substantially the same as the radius r of the grinding wheel G. When the chip discharge groove 4 is twisted as described above, the grinding wheel G is given a predetermined swing angle with respect to the axis O so that the outer periphery of the grinding wheel G follows the twist of the chip discharge groove 4. Grinding is performed by rotating the drill body 1 around the axis O in accordance with the twist of the chip discharge groove 4 and moving the drill body 1 relatively in the direction of the axis O.

[0004]

By the way, in drilling with such a solid drill, the diameter of a circle formed by the outer peripheral end 9 of the cutting edge 6 around the axis O, that is, the outer diameter D of the cutting edge 6 is set. On the other hand, from the normal length of the cutting edge portion 5 of about 5 × D to the longer length of 10 × D or more in some cases, 20 to 25 × D in recent years has been used. In the past, deep holes, which were conventionally done by gun drills, are now often made by such solid drills to improve the working efficiency. However, in such a drill having a long cutting edge portion 3 and performing deep hole machining, the length from the outer peripheral end 9 of the cutting edge 6 to the rear end of the chip discharging groove 4 in the axis O direction, that is, the chip discharging groove length L. Similarly, the length of the chips generated by the cutting blade 6 is also discharged through the chip discharging groove 4 so that the chips are easily clogged. Once such clogging of chips occurs, the resistance to rotation of the drill body 1 increases due to the clogging of chips on the tip side of the cutting edge portion 3, whereas the shank portion 2 on the rear end side of the drill body 1 increases. Since the main shaft of the machine tool continues to hold the rotational driving force, a large twisting force acts on the rear end portion of the cutting blade portion 3 between them, and the groove bottom 8 of the chip discharge groove 4 is applied. In addition to the fact that the drill body 1 is cut up in a concave curved shape with a small radius of curvature as described above, and the thickness of the drill body 1 is cut off,
The drill body 1 was often broken at the rear end portion of the chip discharge groove 4.

The present invention has been made in view of such a background, and provides a drill and a manufacturing method thereof which will not cause breakage due to clogging of chips even in a drill having a long cutting edge portion as described above. Is intended.

[0006]

In order to solve the above problems and to achieve such an object, the drill of the present invention has a chip discharge groove formed on the outer periphery of the tip end portion of the drill body rotated about the axis. , In a drill in which a cutting edge is formed at the ridge line intersecting with the rake face formed on the tip side of the inner peripheral surface of this chip discharge groove and the tip flank of the drill body, the groove bottom of the chip discharge groove, From the rear end of the chip discharge groove toward the tip end side in the axial direction, starting to round up to the outer peripheral side of the rear end within the range of L / 2 of the chip discharge groove length L, in a cross section along the extending direction of the chip discharge groove. It is characterized in that the radius of curvature is a concave curve or a straight line shape of 10 × D or more with respect to the outer diameter D of the cutting edge and reaches the rear end thereof. Therefore, in such a drill, the groove bottom at the rear end portion of the chip discharging groove is rounded up to the outer peripheral side of the rear end so as to form a concave curve-shaped or linear cross-section having an extremely large radius of curvature as described above. Since the thickness of the drill body is reduced at the rear end of this chip discharge groove, that is, the core thickness can be increased, which secures rigidity and strength against twisting of the drill body in that part. As a result, breakage can be prevented.

Further, in order to manufacture a drill having such a structure, in the drill manufacturing method of the present invention, a chip discharge groove is formed on the outer periphery of the tip end portion of the drill body rotated about the axis, and the chip discharge groove is formed. A method for manufacturing a drill in which a cutting edge is formed at a ridge line intersecting with a rake face formed on the tip side of the inner peripheral surface of the drill body and a tip flank of the drill body, and the disc-shaped grinding is performed as described above. When forming the groove bottom of the chip discharge groove by relatively moving the grinding wheel and the drill main body in the axial direction while sliding the outer periphery of the grindstone in the chip discharge groove while slidingly contacting the same, First, from the rear end of the chip discharge groove toward the tip side in the axial direction, the grinding wheel is linearly moved to the outer peripheral side of the rear end of the drill body within a range of L / 2 of the chip discharge groove length L. It is special to move relatively so that it rounds up. Secondly, from the rear end of the chip discharge groove toward the front end side in the axial direction, within the range of L / 2 of the chip discharge groove length L, the grinding wheel is provided on the outer peripheral side of the rear end of the drill body. In addition, it is characterized in that a concave curve having a radius of curvature larger than the outer diameter of the grinding wheel is drawn and relatively moved so as to be cut up. Therefore, according to such a manufacturing method,
Not only when the grinding wheel is cut up linearly like the first method, but also when the grinding wheel is cut up in a concave curve shape having a radius of curvature larger than the radius of the grinding wheel, the rear end of the chip discharge groove of the drill is also used. The radius of curvature of the concave curve formed by the cross section of the groove bottom can be made larger than the radius of curvature according to the radius of the conventional grinding wheel, and the thickness of the drill main body (core thickness ) Can be secured largely.

[0008]

1 to 3 show an embodiment of a drill and a manufacturing method thereof according to the present invention.
In the drill of the present embodiment, the drill main body 11 is made of a hard material such as cemented carbide and has a substantially cylindrical shape centered on the axis O, and its tip side (left side in FIGS. 1 and 3) is a cutting edge portion 12. At the same time, the rear end side (right side in FIGS. 1 and 3) is a shank portion 13. And
On the outer periphery of the cutting edge portion 12, from the tip flank surface 14 of the tip of the drill body 11 toward the rear end side to just before the shank portion 13, as it goes rearward in the direction of the axis O, the rear side of the drill rotation direction T is reached. A pair of chip discharge grooves 15 and 1 that are twisted in a spiral shape
5 are formed to be symmetrical with respect to the axis O,
A portion of the inner peripheral surface 16 of the chip discharge groove 15 that faces the drill rotation direction T side at the tip is a rake surface 17, and a cutting edge 18 is provided at the ridge line portion where the rake surface 17 and the tip flank 14 intersect. Has been formed.

In the present embodiment, the length of the cutting edge portion 12 is at least 5 with respect to the diameter of the circle formed by the outer peripheral end 19 of the cutting edge 18 around the axis O, that is, the outer diameter D of the cutting edge 18. XD or more, 2 when drilling a deep hole as described above
It is set to 0 to 25 × D, and therefore the outer peripheral edge 1 of the cutting edge 18
9, the length of the chip discharge groove 15 from the rear end side to the outer peripheral surface of the cutting edge portion 12, that is, the length in the axis O direction from the rear end 20 of the chip discharge groove 15, that is, the chip discharge groove length L is also Similarly, the length is set to be 5 × D or more, or 10 × D or more, or 20 to 25 × D or more. further,
In the drill body 11, a pair of cutting oil supply passages 21 and 21 are provided from the rear end toward the tip end side of the chip discharge groove 15,
It is formed in a spiral shape so as to avoid 15 and is opened in each of the tip flanks 14.

Further, on the outer peripheral surface between the chip discharge grooves 15 in the circumferential direction of the cutting edge portion 12, a ridge line intersecting with the chip discharge groove 15 spirally twisted on the drill rotation direction T side is formed. A margin portion 22 is formed. The outer peripheral surface of the margin portion 22 has an arcuate cross-section with an outer diameter equal to the outer diameter D of the cutting edge 18, and is provided in the chip discharge groove 15 over the entire length of the cutting edge portion 12 with a small constant width in the circumferential direction. It is extended along. Further, on the rear side of the margin portion 22 in the drill rotation direction T, the margin portion 22 is retracted toward the inner peripheral side of the one-step drill main body 11 with respect to the outer peripheral surface thereof to form an arc-shaped cross section having a small outer diameter. Eggplant outer flank 23
Are formed. The cutting edge 18 and the margin 2
Similarly to the chip discharge grooves 15 and 15, the outer peripheral flank 23 and the outer peripheral flank 23 are also formed in pairs symmetrically with respect to the axis O. A back taper may be given to the margin portion 22 and the outer peripheral flank 23.

Further, in the present embodiment, the groove bottom 24 of the chip discharge groove 15 has a cross section of the drill main body 11 along the twist of the chip discharge groove 15 from the tip flank 14 of the tip of the cutting blade portion 12. The portion extending toward the rear end side is formed parallel to the axis O, or is formed in a linear shape that is slightly inclined toward the inner peripheral side toward the rear end side, while near the shank portion 13 on the rear end side. It is rounded up to the outer peripheral side to reach the outer peripheral surface of the cutting blade portion 12 and reach the rear end 20. The groove bottom 24 of the chip discharge groove 15 is the length of the chip discharge groove 15 from the rear end 20 where the chip discharge groove 15 reaches the outer peripheral surface of the cutting edge portion 12 toward the tip side in the direction of the axis O. It is formed so as to start to rise to the outer peripheral side of the rear end within the range M of L / 2 of L, and further to reach the rear end 20 in a straight line shape as shown in FIG. However, the cross section of the portion where the groove bottom 24 starts to linearly rise to the outer peripheral side of the rear end is in an extremely short range, is parallel to this straight line and the axis O on the front side, or is inclined to the inner peripheral side as it goes to the rear end side. It is a concave curve that smoothly connects the straight line.

Here, the chip discharge groove 1 of such a drill
No. 5 has a disk shape similar to the conventional one until the cross section of the groove bottom 24 on the front end side of the drill body 1 is parallel to the axis O or forms a portion slightly inclined toward the inner peripheral side toward the rear end side. The grinding wheel G is given a swing angle of the grindstone in accordance with the twist of the chip discharge groove 15 and rotated, and the outer peripheral portion thereof is slidably brought into contact with the inside of the chip discharge groove 15, and further the drill main body 11 is adjusted in accordance with the twist of the chip discharge groove 15. While twisting, the drill main body 1 and the grinding wheel G are shown in FIG. 1 so as to be parallel to the axis O from the tip flank 14 side toward the rear end side in the axis O direction or slightly toward the inner peripheral side toward the rear end side. It is formed by relative movement as shown by the arrow B. And in one embodiment of the manufacturing method of the present invention when manufacturing the drill of the above embodiment,
In the portion where the groove bottom 24 of the chip discharge groove 15 cuts up to the outer peripheral side of the rear end within the above range M, while twisting the drill main body 11, as shown by the solid arrow C in FIG. Side to side relative to the outer peripheral side of the drill main body 11, the grinding wheel G relative to the rear end outer peripheral side of the drill main body 11 so as to linearly cut up, through the rear end 20 Make it come out from the chip discharge groove 15. By cutting up the rear end portion of the chip discharge groove 15 in this manner, the open groove portion of the rear end portion of the chip discharge groove 15 to the outer peripheral surface of the cutting edge portion 12 is formed by the conventional drill shown in FIG. As described above, the cross-sectional shape of the outer peripheral portion of the grinding wheel G is not transferred as it is, and as shown in FIG. 1 or 3, the shape gradually becomes smaller toward the rear end 20.

Therefore, in the drill of the above-described embodiment manufactured by such a manufacturing method, the groove bottom 24 in the range M on the rear end side of the chip discharge groove 15 faces the outer peripheral side of the rear end as described above. Since it is rounded up so as to form a linear cross section, if the position of the rear end 20 is the same and the outer diameter of the grinding wheel G is the same, this groove bottom 2 is larger than that of the conventional drill.
It is possible to increase the distance from the axis O of the portion where 4 is cut up to the groove bottom 24, and along with this, it is possible to secure a large thickness (core thickness) of the drill body 11 and improve its rigidity and strength. it can. For this reason, when chip clogging occurs on the tip side of the cutting edge portion 12 whose length is increased as described above, this chip discharge groove 15 immediately before the shank portion 13 is formed.
Even if a large twisting force is applied to the part where the groove bottom 24 of the cutting up part, the drill body 11 can be prevented from being broken from this part, and the drilling of the deep hole by the twist drill can be further performed. It becomes possible to perform surely and smoothly.

Further, in the manufacturing method of the above-described embodiment for manufacturing such a drill, the grinding wheel G is moved relative to the drill main body 11 in the direction of the axis O as in the conventional case, and the chips are removed. It is only necessary to relatively linearly move the discharge groove 15 to the rear end outer peripheral side at the cut-up portion as described above. For example, it is more efficient and easier than the case where the cut-up portion is formed by a different grindstone. Such a chip discharge groove 15 can be formed. Further, according to the present embodiment, the open groove portion to the outer peripheral surface of the cutting edge portion 12 of the cut-up portion of the chip discharge groove 15 is the rear end 2 as described above.
Since it becomes a taper shape toward 0, even in the circumferential direction of the drill body 11, it is possible to reduce the groove width of the chip discharge groove 15 in the vicinity of the rear end 20 and secure the wall thickness thereof. By further improving the rigidity and strength of 11, it is possible to more reliably prevent breakage and the like.

However, in the drill and the manufacturing method thereof according to the present embodiment, the grinding wheel G is linearly moved to the outer peripheral side of the rear end of the drill body 11 as shown by the arrow B in FIG. As a result, the groove bottom 24 of the chip discharge groove 15
Also, the section is cut up linearly so as to reach the rear end 20, but as shown by the broken line D in FIG. 1, the chip discharge from the rear end 20 of the chip discharge groove 15 toward the front end side in the axial direction O. In the range M of L / 2 of the groove length L, the grinding wheel G is cut up on the outer peripheral side of the rear end of the drill body 11 by drawing a concave curve having a radius of curvature R larger than the radius r of the grinding wheel G. By moving it relative to the cutting edge 1, the cross section of the chip discharge groove 15 at the cut-up portion has a radius of curvature R.
It may be formed so as to reach the rear end 20 by forming a concave curve of 10 × D or more with respect to the outer diameter D of 8. Even in such a drill, the wall thickness (core thickness) of the drill main body 11 at the cut-up portion of the chip discharge groove 15 can be ensured to be larger than that of the conventional one, so that the rigidity of the drill main body 11 at the portion is increased. Also, the strength can be improved, and breakage when chip clogging occurs can be prevented.

In these drills and the manufacturing method thereof, the groove bottom 24 of the chip discharge groove 15 is the drill body 1.
The position at which the outer edge of the rear end of the chip 1 starts to rise is within the range M of L / 2 of the chip discharge groove length L from the rear end 20 of the chip discharge groove 15 toward the front end side in the axial direction O. When the groove bottom 24 begins to rise to the outer peripheral side on the tip side of this range M, the groove depth of the chip discharge groove 15 becomes too shallow on the tip side of the cutting edge portion 12, and chip clogging is likely to occur frequently. This is because even if the drill body 11 does not break due to the above-described configuration, smooth and stable drilling may be hindered. Here, in order to ensure the groove depth of the chip discharge groove 15 on the tip side in this manner, for example, when the chip discharge groove length L is 10 × D, the range M is the chip discharge groove 15 From the rear end 20 toward the front end side in the axial direction O to about L / 3 of the chip discharge groove length L, and when the chip discharge groove length L is 20 × D, the range M is the rear end 2
L of the chip discharge groove length L from 0 toward the axial direction O tip side
It is desirable to be about / 5. In addition, in the above-mentioned drill in which the cross section of the groove bottom 24 of this raised portion has a concave curve shape, the radius of curvature R is 10 with respect to the outer diameter D of the cutting edge 18.
If it is smaller than xD, the radius r of the conventional grinding wheel G
There is a possibility that it will not be possible to reliably prevent breakage, as it will be the same as a drill in which the groove bottom rises with a radius of curvature according to.

Further, in order to improve the wear resistance of the cutting blade 18, the tip flank 14 and the margin portion 22 of the cutting blade portion 12 of this type of drill, the cutting blade portion 12 is particularly effective.
For example, TiC, TiN, TiCN, Ti
Coating of a hard coating made of one or more of AlN is carried out, but the surface roughness of such a hard coating is relatively rough as 2 to 4 μm in the as-coated state, and therefore such a hard coating is used. Is the inner peripheral surface 16 of the chip discharge groove 15.
However, if it is still covered, the resistance at the time of chip discharge increases, and chip clogging is likely to occur. Therefore, when coating the surface of the cutting edge portion 12 with such a hard coating, the inner peripheral surface 1 of the chip discharge groove 15
6, a paste containing diamond particles, for example, is applied to a brush and the inner peripheral surface 16 is polished to perform a polishing process, whereby the surface roughness of the inner peripheral surface 16 is covered with a hard coating. It is desirable that the surface roughness of the tip flank 14 or the marginal portion 22 or the peripheral flank 23 as it is is smaller, that is, smoother.

[0018]

As described above, according to the present invention,
Even if the length of the cutting edge is long and a deep hole is to be machined, it is possible to secure the thickness of the drill body at the part where the chip discharge groove rises and improve its rigidity and strength. This makes it possible to prevent breakage of the drill body even if a large twisting force acts on this portion.

[Brief description of drawings]

FIG. 1 is a side view of a drill body 11 and a chip discharge groove 15 in an embodiment of a drill and a manufacturing method thereof according to the present invention.
FIG. 4 is a view showing a cross-sectional view along the twist of No. 1 and the relative movement of the grinding wheel G together.

FIG. 2 is an enlarged front view of the cutting edge portion 12 of the drill of the embodiment shown in FIG. 1 as seen from the tip side.

FIG. 3 is a side view showing a spirally twisted chip discharge groove 15 of the drill of the embodiment shown in FIG. 1 so as to be straight along an axis O;

FIG. 4 is a diagram showing a side view of a drill body 1 in a conventional drill and a manufacturing method thereof, a cross-sectional view along a twist of a chip discharge groove 4, and a relative movement of a grinding wheel G.

[Explanation of symbols]

11 drill body 12 cutting edge portion 14 tip flank surface 15 chip discharge groove 18 cutting edge 20 cutting edge groove 15 rear end 24 groove bottom of chip discharge groove 15 axis T of the drill body 11 drill rotation direction D outside of the cutting edge 18 Diameter L Chip discharge groove length M Range of the chip discharge groove length L from the rear end 20 of the chip discharge groove 15 toward the tip side in the axis O direction

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masayuki Mabuchi             1528, Nakashinden, Yokoi, Kobe-cho, Anpachi-gun, Gifu Prefecture             Address Mitsubishi Materials Corporation Gifu Factory             Within F term (reference) 3C037 DD01

Claims (3)

[Claims] 1. A chip discharge groove is formed on the outer periphery of the tip of a drill body rotated around an axis, and a rake face formed on the tip side of the inner peripheral surface of the chip discharge groove and the tip flank of the drill body. In a drill in which a cutting edge is formed on a ridge line intersecting with, the groove bottom of the chip discharge groove is L of a chip discharge groove length L from the rear end of the chip discharge groove toward the tip end side in the axial direction.
Starts to rise to the outer peripheral side of the rear end within the range of / 2, and in the cross section along the direction in which the chip discharge groove extends, the radius of curvature forms a concave curve or a straight line shape of 10 × D or more with respect to the outer diameter D of the cutting edge. A drill characterized in that it reaches the above-mentioned rear end. 2. A chip discharge groove is formed on the outer periphery of the tip of a drill body rotated about an axis, and a rake face formed on the tip side of the inner peripheral surface of the chip discharge groove and the tip flank of the drill body. Is a method of manufacturing a drill having a cutting edge formed at a ridge line intersecting with the cutting wheel, wherein the disc-shaped grinding wheel is rotated to slide the outer periphery thereof into the chip discharge groove and the grinding wheel and the drill body. While forming the groove bottom of the chip discharge groove by relatively moving and in the axial direction,
From the rear end of the chip discharge groove toward the tip side in the axial direction, the grinding wheel is linearly cut up to the outer peripheral side of the rear end of the drill body within a range of L / 2 of the chip discharge groove length L. A method of manufacturing a drill, characterized in that the drill is moved relative to the drill. 3. A chip discharge groove is formed on the outer periphery of the tip of a drill body rotated about an axis, and a rake face formed on the tip side of the inner peripheral surface of the chip discharge groove and the tip flank of the drill body. Is a method of manufacturing a drill having a cutting edge formed at a ridge line intersecting with the cutting wheel, wherein the disc-shaped grinding wheel is rotated to slide the outer periphery thereof into the chip discharge groove and the grinding wheel and the drill body. While forming the groove bottom of the chip discharge groove by relatively moving and in the axial direction,
From the rear end of the chip discharge groove toward the tip end side in the axial direction, within the range of L / 2 of the chip discharge groove length L, the grinding grindstone is provided on the outer peripheral side of the rear end of the drill body. A method for manufacturing a drill, characterized by drawing a concave curve having a larger radius of curvature and moving relative to it so as to raise it.